Ultrasound system with through via interconnect structure

Abstract

An ultrasound monitoring system. In one embodiment, an array of transducer cells is formed along a first plane and an integrated circuit structure, formed along a second plane parallel to the first plane, includes an array of circuit cells. A connector provides electrical connections between the array of transducer cells and the array of circuit cells, and an interconnection structure is connected to transfer signals between the circuit cells and processing and control circuitry. The integrated circuit structure includes a semiconductor substrate and a plurality of conductive through-die vias formed through the substrate to provide Input/Output (I/O) connections between the transducer cells and the interconnection structure. The monitoring system may be configured as an imaging system and the processing and control circuitry may be external to the probe unit.

1 . An ultrasound monitoring system comprising a probe unit including:
 an array of transducer cells formed along a first plane;   an integrated circuit structure comprising an array of circuit cells formed along a second plane parallel to the first plane;   a connector providing electrical connections between the array of transducer cells and the array of circuit cells; and   an interconnection structure connected to transfer signals between the circuit cells and processing and control circuitry, wherein the integrated circuit structure includes a semiconductor substrate with a plurality of conductive through-die vias formed through the substrate to provide Input/Output connections to the interconnection structure.   
   
   
       2 . The system of  claim 1  configured as an imaging system. 
   
   
       3 . The system of  claim 1  wherein the system includes the processing and control circuitry and the processing and control circuitry is positioned external to the probe unit. 
   
   
       4 . The system of  claim 1  wherein the array of transducer cells includes one or more transducer modules, each module comprising a subarray of transducer cells and a subarray of interface circuit cells. 
   
   
       5 . The system of  claim 1  wherein the transducer cells are cMUTs formed in and about a semiconductor substrate. 
   
   
       6 . The system of  claim 1  wherein the transducer cells are cMUTs of the type having insulative regions formed between adjacent cells, a front electrode common to multiple ones of the transducer cells and a plurality of rear electrodes each connected to transfer a signal between a different circuit cell of the integrated circuit structure and a transducer cell, each rear electrode positioned between the integrated circuit structure and the front electrode, the system further including a conductive via formed within a cMUT insulative region connecting the front electrode to the interconnection structure. 
   
   
       7 . The system of  claim 1  wherein the integrated circuit structure includes a metallization structure providing a redistribution function including a conductive segment parallel with the first plane in order to accommodate an offset between one of the transducer cells and one of the circuit cells. 
   
   
       8 . The system of  claim 5  wherein the connector includes a series of conductive paths, each connected between one of a plurality of upper flex contact pads and one of a plurality of lower flex contact pads, functioning as a redistribution system. 
   
   
       9 . The system of  claim 5  wherein a plurality of through-vias are formed in the transducer semiconductor substrate. 
   
   
       10 . The system of  claim 1  wherein the semiconductor substrate has a thickness in the range of 25 microns to 200 microns. 
   
   
       11 . The system of  claim 1  wherein the integrated circuit structure is bonded to a backing substrate taken from the group consisting of a semiconductor substrate and a glass substrate coated with an amorphous silicon layer. 
   
   
       12 . The system of  claim 1  wherein the connector comprises a flexible circuit assembly having one or more flexible circuits for routing electrical connections between the integrated circuit cells and the transducer cells. 
   
   
       13 . The system of  claim 1  wherein the interconnection structure comprises a flexible circuit assembly having one or more flexible circuit boards for routing electrical connections to the processing and control circuitry. 
   
   
       14 . An ultrasound monitoring system comprising a probe unit including:
 an array of transducer cells formed along a first plane and an integrated circuit structure comprising an array of circuit cells formed along a second plane parallel to the first plane, the array of transducer cells including insulative regions formed between adjacent transducer cells, a front electrode common to multiple ones of the transducer cells and a plurality of rear electrodes each connected to transfer a signal between a different circuit cell of the integrated circuit structure and a transducer cell, each rear electrode positioned between the integrated circuit structure and the front electrode;   a connector configured to effect the electrical connections between the rear electrodes and circuit cells in the integrated circuit structure; and   an interconnection structure connected to transfer signals between the circuit cells and processing and control circuitry, the system further including a conductive via formed in one of the insulative regions between adjacent ones of the transducer cells effecting an electrical connection to the interconnection structure.   
   
   
       15 . The system of  claim 14  wherein the integrated circuit structure includes a semiconductor substrate with a plurality of conductive through-die vias formed through the substrate to provide Input/Output connections to the interconnection structure. 
   
   
       16 . The system of  claim 14  wherein the transducer cells are cMUTs formed in and about a semiconductor substrate. 
   
   
       17 . The system of  claim 14  wherein the conductive via formed within one of the insulative region effects a ground connection to the front electrode. 
   
   
       18 . An ultrasound system comprising a probe unit including:
 an array of transducer cells formed along a first plane, wherein the transducer cells are formed in or on a transducer substrate having a plurality of conductive through vias for transferring signals;   an integrated circuit structure comprising an array of circuit cells formed along a second plane;   a connector providing electrical connections between the through vias in the array of transducer cells and the array of circuit cells; and   an interconnection structure connected between the circuit cells and a connector portion to transfer signals between the circuit cells and processing and control circuitry external to the probe unit, wherein a plurality of conductive through-die vias are formed through the integrated circuit structure to provide Input/Output connections between the transducer cells and the interconnection structure.   
   
   
       19 . The system of  claim 18  wherein the system is configured for image processing and the through vias in the transducer substrate provide electrical connections between the transducer cells and the connector. 
   
   
       20 . A method of forming a large area transducer assembly, comprising the steps of:
 providing an array of transducer cells along a first plane with a first pitch along a first direction;   providing an integrated circuit device comprising an array of circuit cells with a plurality of conductive through-die vias extending through the circuit cells to make electrical connections between the circuit cells and the transducer cells;   providing a connector for making electrical connections between the conductive through-die vias and the array of transducer cells; and   providing an interconnection structure for effecting input/output connections to the integrated circuit device.   
   
   
       21 . The method of  claim 20  further including the step of providing an array of transducer cells formed in or on a transducer substrate, the transducer substrate having a plurality of conductive through vias for making electrical connections between the transducer cells and the conductor. 
   
   
       22 . The method of  claim 20  wherein the step of providing the integrated circuit device includes providing a substrate, thinning the substrate in the range of 25 to 200 microns and forming the through-die vias after thinning the substrate. 
   
   
       23 . The method of  claim 22  further including steps of:
 providing a backing substrate; and   bonding the thinned integrated circuit device and the backing substrate by direct fusion bonding.   
   
   
       24 . The method of  claim 22  further including the steps of:
 providing a rigid connector; and   bonding the integrated circuit device and the connector by direct fusion bonding or thermal compression bonding.   
   
   
       25 . The method of  claim 23  wherein the integrated circuit device is thinned to an overall thickness of between 25 microns and 200 microns. 
   
   
       26 . The method of  claim 20  wherein the step of providing the integrated circuit device includes providing a substrate, thinning the substrate to an overall thickness ranging between a characteristic junction depth of the CMOS fabrication process and 200 microns and forming the through-die vias after thinning the substrate. 
   
   
       27 . The method of  claim 21  further including providing a dematching layer or acoustic backing between the transducer cells and the connector.